2004/03/31 by P. Chris Fragile, Peter Anninos · 5 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/428433
51 pages, 34 figures (color figures reduced for this archive), this version accepted to ApJ
arxiv created 2005/01/07 · openalex publication_date 2005/04/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present results from fully general relativistic three-dimensional numerical studies of thick-disk accretion onto a rapidly rotating (Kerr) black hole with a spin axis that is tilted (not aligned) with the angular momentum vector of the disk. We initialize the problem with the solution for an aligned, constant angular momentum, accreting thick disk, which is then allowed to respond to the Lense-Thirring precession of the tilted black hole. The precession causes the disk to warp, beginning at the inner edge and moving out on roughly the Lense-Thirring precession timescale. The propagation of the warp stops at a radius in the disk at which other dynamical timescales, primarily the azimuthal sound-crossing time, become shorter than the precession time. At this point, the warp effectively freezes into the disk, and the evolution becomes quasi-static, except in cases where the sound-crossing time in the bulk of the disk is shorter than the local precession timescale. We see evidence that such disks undergo near solid-body precession after the initial warping has frozen in. Simultaneous to the warping of the disk, there is also a tendency for the midplane to align with the symmetry plane of the black hole as a result of the preferential accretion of the most tilted disk gas. This alignment is not as pronounced, however, as it would be if more efficient angular momentum transport (e.g., from viscosity or magnetorotational instability) were considered.